Peterson Field Guide to Backyard Birds This is a beautiful app that lets you identify the birds you see with pictures and a clear description.

Bird Watching for Beginners This gives a nice abbreviated guide to bird watching: equipment needed, where to find birds, creating a desirable landscape for them in your own backyard. More of an E-book than a guide, but a good start for bird watching noobs.

bird glossary This is basically an encyclopedia of birds that gives a plethora of information on different breeds, the main lacking element however is a picture of the bird.

WhatWhereWhen This is a bird watching diary that makes keeping track of your sightings a breeze. However the open nature of this app allows you make this a sighting journal for pretty much anything: animals, flowers, even celebrities if you are so inclined.

Bird Watching Manual This is another e-guide to birdwatching with all the information you need to get started with your bird watching hobby.